FIELD: physics.
SUBSTANCE: method uses ultrasonic property of the valuable document for recording the measurement data with the spatial resolution and the formation depending on measurement data location. The method uses measurement data depending on the location, and the check is performed, whether there are two surface areas on the predetermined checking area of the valuable document, so that, at least, one ultrasonic property at the locations on the first of the two surface areas has the predetermined first character, and, at least, one ultrasonic property on the first surface area and, at least, one ultrasonic property on another surface area. The areas differ from each other according to the predetermined difference criterion, wherein the authentication signal is formed, which reflects the check results. In addition, the corresponding check device is described.
EFFECT: increasing the reliability of checking primarily the counterfeit of banknotes made up of several parts.
30 cl, 9 dwg
